This invention relates to a sheet having an elastic stretchability longitudinally and transversely thereof.
It is well known to obtain a nonwoven fabric of comfortable touch by a process comprising the steps of a continuously feeding web of elastically stretchable fiber and treating this with heated emboss-rolls or high pressure column-shaped water streams so that the composite fibers may be heat-sealed together or mechanically intertwined together. Such a nonwoven fabric has conventionally used in various garments such as disposable diapers or sanitary napkins.
In the case of the known nonwoven fabric, the elastic component fibers are apt to be oriented in coincidence with the machine direction during a step of making the web or the subsequent step of treating the web. Consequently, the nonwoven fabric obtained is easily stretchable in the machine direction but often inadequately stretchable in the direction orthogonal to the machine direction.
It is an object of this invention to make an elastically stretchable sheet being intrinsically stretchable in one direction but not in the direction orthogonal to the one direction stretchable in these two directions.
According to this invention, there is provided a sheet having an elastic stretchability both in a longitudinal direction thereof and in a transverse direction orthogonal to the longitudinal direction, wherein: a flat sheet material intrinsically having a nature of being elastically stretchable in the longitudinal direction without any significant resistance rather than in the transverse direction is formed with a plurality of pleats extending in the longitudinal direction and having a plurality of crests and troughs alternately repeating in the transverse direction and a plurality of elastic members being stretchable in the transverse direction are secured to respective apices of the plurality of crests forming the pleats from outer side.
According to one preferred embodiment of this invention, the elastic members are secured also to respective bottoms of the plurality of troughs forming the pleats from outer side.
According to another preferred embodiment of this invention, the elastic members are provided in the form of elastic threads and according to still another preferred embodiment of this invention, the elastic members are provided in the form of a sheet having an elastic stretchability both in the longitudinal direction and in the transverse direction.